Yes, I can see how making prize cars purchasable makes them available multiple times, however the alternative is MAKING THEM WINNABLE MORE THAN ONCE. Plus the carousel can now be implemented. 2 improvements at once!
Yeah the prize cars are a bit rubbish but the main thing for me is not being able to re win cars to make money off them. Sure initialy it is probably easier to make money but then when you start to grind and save it doesnt really feel like you are getting anywhere once you need more expensive cars for races and you cant win them. It will probably affect the replay value of the game to a lot of people.